No federally sponsored research or development, and no sequence listing, table, or computer program listing or compact disc appendix is applicable to this application.
The field of the presently described apparatus relates to space frame structures, and particularly to node elements, fixtures where two or more struts of the frame are joined. Examples of such nodes are disclosed by Ventrella, U.S. Pat. No. 4,480,418, “Modular System for Space Grid Structures,” Cook, U.S. Pat. No. 4,974,986, “Connector for Variable-Shape Spaceframe Structural System,” Lange, U.S. Pat. No. 4,982,546, “Space Frame Node,” Lalvani, U.S. Pat. No. 5,265,395, “Node Shapes of Prismatic Symmetry for a Space Frame Building System,” and Mhaimeed, US 2002/0150444, “Special Bolt and Sleeve Combination for Use in Tube-And-Node Space Frame Systems . . . ”
A space frame is typically a lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports such as columns. Like the truss, a space frame is strong because of the inherent rigidity of the triangle where flexing loads and bending moments are transmitted as tension and compression vectors along the length of each strut. The simplest form of the space frame is a horizontal slab of interlocking square pyramids which might be built from aluminum or tubular steel struts interconnected by fixtures generally referred to by the term “node.” This structure may look like the horizontal jib of a tower crane repeated many times to make it wider. A stronger form may comprise interlocking tetrahedral pyramids in which all the struts have unit length. More technically, this is referred to as an isotropic vector matrix, or in a single unit width, an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.
Space frames are common in building construction such as large roof spans in modern commercial and industrial buildings. Notable examples of buildings based on space frames include: Stansted airport in London, Bank of China Tower and the Louvre Pyramid, Rogers Centre, McCormick Place East in Chicago, Eden Project in Cornwall, England, Globen, the Swedish dome structure which has a diameter of 110 m, and Biosphere 2 in Oracle, Ariz. Large portable stages and lighting gantries are also frequently built from space frames with octet trusses. Today, the octet truss is the structure of choice for holding signs above roads in the United States.
Space frames have been used in automobile and motorcycle chassis wherein the engine and body panels are suspended, and the body panels have little or no structural function. By contrast, in a monocoque design, the body serves as the primary stress bearing and load transferring structure. Tube-frame chassis, adopted from the space frame, are frequently used in racing car designs. The first notable american-produced automobile to incorporate a space frame was the Pontiac Fiero. Fiero frames used 233 individual pieces of steel, weighing in at 6001 bs, to form a very strong and safe automobile. After the Fiero program ended in 1988, this technology was adopted for the Saturn SL series, Pontiac Trans-Sport, and Chevrolet Lumina APV mini-vans. British manufacturer TVR is particularly well known for their tube-frame chassis designs, produced since the 1950s. Other notable examples of tube-frame cars include the Audi A8, Lotus Seven, Ferrari 360, Lamborghini Gallardo, and Mercedes-Benz SLS AMG.